Dryer



July 21, 1970 D. c. SANDERS. JR 3,521,375

DRYER Filed May 16. 1968 4 Sheets-Sheet 1 FIG.!

| I I8 INVENTOR.

I DEWEY c. SANDERS,JR.

l /fiTfiTIEY July 21, 1970 -D. c. SANDERSLJR 2 v DRYER Filed May 16.1968 V 4 Sheets-Sheet 2 INVENTOR. DEWEY C. SANDERS,JR.

I W :izxzzv July 21; 1970 D; c. SANDERS. JR 3,521,375

DRYER Filed may 16. 1968 4 Sheets-Sheet 5 I v:; m I ""1 I, I II V I IINVENTOR.

L B L FIG. 5

DEWEY G. SANDERS,JR.

July 21, 1970 D. c. SANDERS. JR

DRYER 4 Sheets-Sheet 4 Filed May 16. 1968 FIG. 6"

- YNVENTOR. DEWEY C. SANDERS, JR.

/ A TQRNQ FIG. '7

United States Patent Office Patented July 21, 1970 US. Cl. 34-44 7Claims ABSTRACT OF THE DISCLOSURE Drying apparatus for drying fibers inyarn or fabric as a continuous length element, and more particularly adrying apparatus in a machine for impregnating such fiber with a liquidfiber-to-rubber adhesive coating in the manufacture of tires, beltingand similar products, wherein the element is rapidly dried at acontrolled temperature by flame generated infra-red type heating meanswhile moving a gas stream rapidly over the surface of the element andprotecting the heating means by a shielding means from the flowing gasstream against any adverse effect on the infra-red radiation from theheating means.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates todryers, and more particularly to dryers for fibers (whether in yarn,cord, fabric, etc. form), especially such fibers to be used in themanufacture of tires, belting and other rubber products.

The rubber products industry uses various fibers for reinforcement,including rayon, nylon, polyester, fiber glass, etc. and may use now orhereafter other natural and artificial fibers. The term fiber, unlessotherwise modified, is intended to be used in its generic sense toinclude all of these fibers. This machine is adapted to process bydipping and drying any continuous length element, such as a woven fabricmade up of cord formed of fibers, a yarn made up of fibers before beingtwisted into cord and woven into fabric, etc. Dipping the yarn isusually done where application of the adhesive over the entire surfaceof the fiber is desired, such as with fiber glass; while other fibersare dipped in the fabric form. Therefore, the terms continuous lengthfiber element, continuous length element, fiber element" or element usedherein, unless otherwise modified, are each intended to cover anycontinuous length yarn, cord or fabric since each is composed of fibers.The term fabric unless otherwise modified, is intended to cover anysuitable fabric, including square-woven fabric and including so-calledcord fabric used for tires and having a fairly open and loose weavewherein the cords form the warp and a comparatively small number of fillthreads connect the cords solely to facilitate handling.

It is well known that before any such element made of textile materialcan be incorporated into rubber articles, especially those to besubjected to drastic conditions of flexing or bending, the fibersthereof must be prepared by coating or impregnating with an adhesivethat will bond well to both rubber and the fibers. These adhesives aredispersed, dissolved or suspended in a liquid vehicle, generally water,into which the element is dipped and subsequently dried.

Such elements have been dried by blowing hot air through a drying ovenin a relatively low temperature. Because of the low drying temperatureand the attendant low speed of operation, large capacity drying ovenshave been necessary so as to require vast expenditures of capitalandlarge factory areas for operation. It has been recognized that ifsuch elements could be dried more rapidly, but at a controlledtemperature to prevent deterioration of the fiber, the speed of dryingcould be vastly increased, or the size and capacity of the dryingapparatus could be considerably reduced.

This invention is an improvement on the invention disclosed in the T. M.Kersker et al. US. Pat. No. 3,250,641, granted May 10, 1966, andentitled Method of Processing Tire Cords, Tire Cord Fabric, And The Likewherein infra-red radiation is used to speed up the drying and many ofthe problems in such element processing for rubber goods manufacture areexplained in some detail to which reference may be had if desired. Thedryer must be of sufficient size to dry the adhesive liquid coatingsufficiently so that the coating will not be picked off or ruptured bythe support means engaged following the drying step.

This invention is also an improvement on the co-pending US. patentapplication Ser. No. 729,282 entitled.Dryer or Heater filed May 15, 1968by Grover W. Rye and Alexander V. Alexeff by the addition of a burnerflame shielding means to this type dryer with suitable modification ofthe gas flow, and the disclosure of that application is incorporatedherein by this reference thereto.

- The present invention relates to an apparatus for drying suchcontinuous length element in a machine for impregnating such elementwith a liquid fiber-to-rubber adhesive in a coating in the manufactureof tires, belting and other rubber products, wherein the element israpidly dried at a controlled temperature by flame-generated infra-redtype heating means while moving a gas stream rapidly over the surface ofthe element and protecting the heating means by a shielding means fromthe flowing gas against any adverse effect on the infra-red radiationfrom the heating means.

An object of the present invention is to provide an apparatus forrapidly and uniformly drying a fiber containing element at a controlledtemperature so as to manufacture a maximum quality article by minimumsized equipment.

Another object of the present invention is to provide a method of dryingfibers at a very high temperature and speed without detriment to thefibers or any coating thereon.

These and other objects of the present invention will become more fullyapparent by reference to the appended claims as the following detaileddescription proceeds in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is an elevational schematic vertical view, partially in section,of a machine or apparatus for coating such element and subsequentlydrying the coating in a drying tower;

FIG. 2 is a side elevational view of two of the drying apparatuseslocated within the drying tower, having some parts omitted or cut away,and having opposed heating zones sandwiching therebetween opposite facesof the element;

FIG. 3 is a top plan view, taken generally along the line 3-3 in FIG. 2,and showing only the element and the gas moving means for dischargingthe gas streams into and through the heating zones and subsequentlydischarging it from the apparatuses in FIG. 2;

FIG. 4 is a perspective view by the fabric of one of the heatingapparatuses in FIG. 2 with some parts omitted or cut away for clarity;

FIG. 5 is a horizontal sectional view, taken generally along the line 55in FIG. 4, through the discharge nozzle and showing its adjustable flowcontrol gate means;

FIG. 6 is an enlarged, schematic, side elevational view with partsomitted or cut away showing the infra-red heating and gas stream actionon the element and certain selected parts in FIG. 2;

FIG. 7 is an electrical and fluid flow diagram of the solenoid gas valvecontrolled main burner gas line to the infra-red burners, a valvecontrolled flow diagram of the fluid system for the burner panelretracting cylinder and gas fiow damper cylinder, and the electricalcirciut for controlling the solenoids operating these valves in responseto the travel speed of the processed element; and

FIG. 8 is a top plan view taken generally along the line 8-8 in FIG. 2of the gas stream flow duct, infrared panels and reflector meanssurrounding the element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 of the drawingsshows machine 10 for treating continuous length fiber element 12 byapplying adhesive thereto and subsequently drying the adhesive withmachine 10 including drying tower 14 (taking the form of either aseparate tower or one zone of an element processing building) havingstructural members 14a supporting sixteen substantially identical dryingapparatuses or dryers 16, to be described in more detail hereinafter.

Although machine 10 can be used for treating any suitable fiber element12 (such as yarn, cord or fabric), a woven fabric will be specificallyused hereafter in this description with this fabric having a lengthdimension L along its direction of movement T by drive rolls 22, 23 and24; a width dimension W transverse thereto; and opposite, generallyparallel faces F1 and F2.

Since each apparatus 16 is especially adapted for driving moisture outof fibers or fabric, it should be apparent that it has many other uses,such as driving moisture out of woven fabric before calendering in themanufacture of rubber goods.

Machine 10 in FIG. 1 sequentially moves fiber element 12 in traveldirection T from feed roll 21 through coating means 18, through dryingtower 14 having sixteen drying apparatuses 16 with each having infra-redheating means 28, over drive roll or support means 24 with fiber element12 freely supported between drive rolls 23 and 24 from the bottom orinlet to the heating zones 40 provided by drying tower 14, and ontowind-up roll 25 or to subsequent heat treating and/ or other processingequipment.

Coating means 18 includes tank 20 containing any well-knownfiber-to-rubber adhesive 19 dissolved, dispersed, or suspended in aliquid vehicle. Such adhesive is generally based onresorcinol-formaldehyde resins and latex in a aqueous medium.

Suitable drive means is provided for relatively moving element 12through machine 10' comprising coating means 18 and drying tower 14.This drive means takes the form herein of suitable tensioning or supportrolls 22, 23 and 24 with any one or all driven by a suitable motordriven drive or independent motors to advance element 12, throughmachine 10 and to apply suitable tension to element 12. When fabricelement 12 has a width W of about 60 inches, 2,000-25,000 pounds tensionthereon will be the operating range for different fibers, and thistension is used for further processing thereof after the adhesive hasbeen dried and for maintaining the fabric taut and planar againstlateral deflection and flapping by gas streams 42 mentioned hereafter.

Element 12 is freely supported in drying tower 14 so that the coatingthereon will not be damaged during the drying thereof. There must besufficient drying capacity in tower 14 to dry the liquid coatingsufiiciently so that the coating will not be picked off or ruptured bysupport roll 24. Hence, it is preferable not to use a drum-type dryer orany other type cylindrical supports in the heating zones 40 because theywill tend to pull off the adhesive covering. Also, an air cushion cannotbe used to suitably support cord fabric on such drum or roller since theair would quickly penetrate any open weave of the fabric and the 25,000pounds maximum tension would quickly bring the fabric into contact withthe cylindrical surface.

It has been found in practice that drying apparatus 16 in tower 14manufactures maximum quality element 12 with minimum equipment size.

Machine 10 has a plurality of drying apparatuses 16 therein for dryingthe fibers in the yarn or fabric in continuous length element 12. Theseare arranged in eight tiers T1T8, and in two banks B1 and B2 so thateach of sixteen apparatuses 16 therein may be identified as to location,as to tier and bank, such as the apparatus in the lower lefthand cornerof FIG. 1 being identified as drying apparatus 16 in tier T1, bank B1.Apparatuses 16 in each bank are arranged in series along the length ofthe fabric in the tiers while any two horizontal apparatuses 16 inopposite banks B1 and B2 and in the same tier are arranged on oppositesides of fabric element 12 as it passes through drying tower 14.Apparatus 16 in each tier and bank has a width wider than fabric element12, as shown in FIGS. 3, 4 and 8, to provide a proper drying action aswill be brought out in more detail hereinafter.

DRYING APPARATUS 16 The remainder of this application will be directedtoward the specific structure, mode of operation and advantages of eachsubstantially identical drying apparatus 16 considered either alone orin any tier or bank combination. The explanation hereinafter of dryingappara tus 16 will emphasize the details in apparatus 16 in tier T2,bank B1 even though all sixteen apparatuses 16 in FIG. 1 are identicalin construction except the two apparatuses in each tier have some commonoperating parts (see FIGS. 2, 3 and 8) and the apparatuses in bank B1are substantially mirrOr images of those in bank B2. Then, the structureand mode of operation common to the two horizontally aligned apparatuses16 in tier T2 for both banks B1 and B2 will be described; later, theeight series arranged and vertically aligned apparatuses 16 in tiersT1-T8 in bank B1 will be described.

For reference herein a typical operating example of apparatus 16 will begiven now. It has been found that an actual operating drying apparatus16 operates satisfactorily with approximately the following dimensionsand operating characteristics (herein referred to as Table I):

' Fabric element 12:

Water picked up was equal to weight of fabric. Tension 2,00025,000pounds.

Air, F 164 Approximate dimensions within frame 30 of burner panel 31 forburners 32 and spacer blocks 33:

Height 4' Width 5 6" Discharge nozzle 50:

Dimensions 50W 1 /2" Dimension 50L 5 9" Without Screen 64 With Screen 64Discharged air velocity (Feet per minute) 4, 000-5, 000 Air dischargedquantity:

C2210 feet per minute output of fan 1 Maximum.

Temperatures at downstream side of drying apparatus 16 at exhaust nozzle56 at top of apparatus 16 With Screen Without Screen 64 64 Each dryingapparatus 16 includes heating means 28, preferably of an infra-redemitting or radiating type, for drying element 12. Although heatingmeans 28 may use any suitable infra-red source, such as an electricquartz tube heating element, etc., it is preferred to use herein aninfra-red heater 32 having a fluid (preferably natural gas) fired flamefor generating infra-red radiation because of its economy of operation,rapid cooling, efiicient heat transfer, and desirable radiatingcharacteristics. One suitable form of heater 32 is that disclosed in US.Pat. No. 2,775,294 granted Dec. 25, 1956 to G. Schwank and entitledRadiation Burners wherein a gas-air mixture burns on the outer surfaceof plate 7 in that patent to heat it to incandescence causing thissurface to emit infrared radiation then striking and heating element 12.Such burner 32 has a metal screen mounted about inch from this radiantsurface, extending parallel thereto, and being substantially coextensivewith this surface serving as a red-radiating screen to increase theburner efiiciency and to assist in providing a uniform distribution ofinfrared radiatnt energy in the manner well known in the art. Then,combustible gas mixed with air burns so that the outer radiating surfaceof plate 7 has a visibly radiant temperature of approximately 1300F.1600 F. with the radiation intensified by the re-radiating screen.

Heating means 28 includes infra-red heating panel 31 in FIG. 4 havingspacer blocks 33 and heaters 32 (shown schematically by diagonal linesin FIG. 4) arranged in a checkerboard-type pattern within its frame 30to provide a planar, radiating face on panel 31 parallel to and facingelement 12 surface F1.

The intensity and pattern of radiation desired may be varied. Since theintensity of radiation generally varies inversely as the square of thedistance between the objects since one considers a point source ofradiation radiating out over the entire interior surface of asurrounding sphere, it would be logical to assume that changing thedistance between the radiating face of panel 31 and element surface F1would be the desirable way of changing the intensity of radiation onsurface F1. This is not true here since the radiating face of panel 31is not a point radiating source but is approximately parallel andcoextensive with surface F1 in heating zone 40. Hence, radiationintensity is not effected by the distance between the radiant face ofpanel 31 and element surface F1. Even the radiation that might normallyescape outwardly horizontally in the space between panel 31 and face F1is held between their parallel faces and reflected back onto fabricelement face F1 by reflector plates 90, which will be described in moredetail hereinafter. Therefore, the desirable way to change the intensityand pattern of radiation desired is to change the number of heaters 32and the number of spacer blocks 33 located within frame 30 of panel 31and to change their distribution within frame 30.

Each heater 32 and panel 31 is fed by gas main line 34 in FIGS. l and 2.Gas entering drying tower 14 through gas main line 34 travels in FIG. 2either: (1) through solenoid gas valve 35 to be mixed with air by airmixer 35a before going through main burner gas line 37 into verticallyextending manifold 37a on the back of panel 31 having flexible hoses 39,one leading from manifold 37a to each infra-red burner 32, or (2)through pilot gas line 36 to the burners on the radiant face of panel31. Any suitable conventional igniter and safety features are provided.Each gas line 36 and 37 has pivotal connections 38 therein adapted topermit pivoting of the line components about a horizontal axis duringhorizontal movement of radiant heating panels 31 between solid anddot-dash line positions in FIGS. 2 and 6, as will be described in moredetail hereinafter.

Each infra-red heating panel 31 heats an infra-red heating zone 40 onthe outer surface of element 12, such as on face F1 or F2, and thedesired action in each heating zone 40 is to rapidly and uniformly dryfabric element 12 at a controlled temperature. This action is obtainedin the present disclosure by rapidly and uniformly evaporating themoisture by the infra-red radiation from panel 31, and by rapidly anduniformly removing by mass transfer the evaporated liquid molecules andheat from fabric element 12 in this heating zone 40 by drying apparatus16. The following paragraphs will explore this mode of operation morecarefully and more specifically.

Infra-red radiation from burner 32 is an efiicient method of heattransfer to provide the energy necessary to evaporate the water into itsvapor form and is much better than many other type high temperatureheating sources. Infra-red waves extend over the spectrum in wave lengthfrom 0.8 to 300 microns from the near infra-red to the far infra-redrange. There is a broad absorption band for water, several microns wide,about at 3.0 microns wave length in the near infra-red region wherewater is evaporated most quickly and most efficiently. Theaforementioned Schwank-type infra-red burner 32 emits strong radiationin this absorption band for water vapor for efliciently and rapidlyvaporizing the water or aqueous molecules in the coating. The moisturewithin the fibers and adhesive coating is heated and evaporated withinthe time period necessary to dry the adhesive coating on the surface ofthe fibers while still permitting the moisture to escape therefrombefore the outer surface of the adhesive is dried and/or curedsufiiciently to form a skin or crust entrapping the remaining moisture.

Any suitable gas may be used, but air is specifically used herein eventhough the generic term gas is used wherever appropriate since anysuitable gas may be used. A gas moving means moves gas stream 42 withrespect to outer surface P1 of element 12 through heating zone 40 duringinfra-red heating thereof for scrubbing this surface F1 and removing bymass transfer aqueous vapor molecules so as to rapidly dry element 12 ata controlled temperature. Stream 42 is a rapidly flowing river of gasblowing at surface F1 and traveling along surface F1 being dried by theinfra-red. With fabric element 12 saturated with water based chemicals19, a fast rate of drying of element 12 to remove the water is highlydesirable. Fast drying results in minimum equipment size, improvedcontrol of drying conditions, and improved quality of element 12. Theevaporated liquid molecules carried away by stream 42 include, ofcourse, not only water molecules but molecules of any volatile material.

The rate of drying is increased by removal of liquid molecules fromsurface F1 to allow better penetration of infra-red energy and by theeflicient mass transfer of water molecules to the gas by a scrubbing orvacuuming action of surface F1 by flowing stream 42. Flowing stream 42also removes convectional heat from drying zone 40 and from fabricelement 12 so as to provide a rigid control of the temperature of thefabric element so that it will not exceed the safe limit. The gas instream 42 is cool enough to cool element 12 as it passes across it. Thisis a peculiar problem to a fabric, such as nylon, some types of whichmight be damaged if the temperature exceeded 250 F. Not all objectsdried require this close temperature control by cooling; for example,ceramics, painted metal parts, etc. preferably pick up as much of heatas possible and cooling is not desired since cooling is a detriment toeflicient operation. It should be apparent that velocity of stream 42will effect the extent of scrubbing action and rate of drying overallquantity of air flowing in stream 42 will effect both rate of drying andheat removal. Preferred condition of the gas in stream 42 is arelatively dry and cool gas, such as air at ambient conditions. The coolgas will have a greater capacity for heat pickup, and the dry gas willpick up the moisture and other evaporated molecules more quickly and ismore transparent to infra-red radiation from panel 31. Moisture ladengas interferes with the transmission of infra-red rays (because itabsorbs this infra-red radiant energy) and interferes with eflicientdrying and heat transfer. Therefore, if gas stream 42 is heavily ladenwith moisture, it may substantially prevent transmission of theinfra-red rays from panel 31 to surface F1 and may serve as aninsulating layer over surface F1 to prevent removal of heat and watervapor. Hence, recirculation of the gas in stream 42 would not bedesirable because it would be hotter than desired so could not pick upmore heat and could not cool element 12, and might well be saturatedwith evaporated molecules, such as water molecules, which wouldinterfere with infra-red transmission and pickup of evaporated watermolecules. Hence, gas stream 42 permits infra-red heaters 32 to operateat their most eflicient temperature, is located as close as possible tofabric face F1 for fast drying, and still permits accurately controllingthe surface temperature of element 12 to prevent damage thereto. Notethat the infra-red radiation from heaters 32 strikes heating zone 40 toprovide drying at the same time as gas stream 42 scrubs the heatingzone. This action provides most rapid drying with minimum sizeequipment.

The aforesaid gas moving means includes gas discharge means fordirecting gas stream 42 as a gas layer or gas curtain generally alongand over surface F1 in heating zone 40 to provide the aforedescribedscrubbing action. Since air of the condition described in the precedingparagraph is preferred, relatively cool, dry air at ambient conditionsis drawn in through inlet duct 46 in FIGS. 1, 2 and 3 (shownschematically in FIG. 1 as two inlet ducts 46 for each tier forsimplicity of illustration instead of the single inlet duct 46 in FIGS.2 and 3) by motor driven, discharge, fresh air or inlet fan 44 in FIG. 3to be forced through nozzle duct 48 and out nozzles 50 in FIG. 2 to formtwo gas streams 42. Each gas discharge nozzle 50 is a rectangular outlethaving its length 50L in FIGS. 4 and 5 many times greater than its width50W. Nozzle 50 also has mounted on duct 48 by screws 53 adjustablecutoff plate 52 and has mounted on duct 48 deflector 54 described inmore detail hereinafter.

Discharge nozzle 50 is preferably mounted so that length dimension 50Lis generally parallel to surface F1 of element 12 in heating zone 40 andwidth dimension 50W is generally perpendicular to surface F1 with nozzle50 directing its discharged gas generally along surface F1 in heatingzone 40 from the lower edge of this heating zone. It should be apparentthat scrubbing action and heat removal will be obtained by having thedischarged stream from nozzle 50 directed transversely across,

longitudinally with (in co-current flow), or longitudinally against (incontraflow) travel direction T of element 12 Directing stream 42 acrosstravel direction T (across element 12 width W) would not be desirablebecause stream 42 would not uniformly hit each portion of width W offabric element 12 so that the fabric would not be uniformly processedacross its width. Nozzle 50' may be mounted near one edge of heatingzone 40 with its length dimension 50L generally parallel to widthdimension W of fabric element 12 with air stream 42 directed in heatingzone 40 generally along the length of movement T of element 12 either inthe same direction (in co-current flow) or the opposite direction (incontraflow) to the movement T for generally uniformly removing liquidmolecules over width W of element 12 to give width W uniform processing.Although stream 42 directed opposite to the direction of travel T (incontraflow) would give an effective scrubbing action, it has been founddesirable to mount nozzle 50 at the bottom of heating zone-40, as shownin FIGS. 4 and 6, so that gas stream 42 is directed in direction T ofelement 12 (in co-ourrent flow) with this direction being upward so thatthe natural convection will help move gas stream 42 toward gas exhaustvent 56.

Nozzle length dimension 50L should be at least as wide as widthdimension W of fabric element 12 so that gas stream 42 will uniformlyeffect each increment of the fabric across its width as it travels indirection T. Dimension 50L should be preferably greater than fabricwidth W so that the lower velocity components in gas stream 42 emergingfrom the lengthwise ends of nozzle 50 do not travel across surface F1and a more uniform velocity layer of gas in stream 42 travels along thelength of element 12.

It is desirable to provide a generally uniform quantity of gas flowingover each portion of fabric element width W in heating zone 40 forgenerally uniformly removing the liquid molecules across this width Wand for maintaining a generally uniform temperature across fabricelement width W in heating zone 40 since drying and heat removal aredirectly proportional to the quantity of gas flowing in stream 42 andsince the scrubbing action is proportional to the velocity of flowingstream 42. This uniform distribution of gas across width W may beobtained either by carefully designing nozzle 50 and maintaining itswidth 50W constant while providing certain desirable gas turning vanesand baffles within nozzle duct 48 and closely adjacent nozzle 50 tocontrol the distribution of gas flow to nozzle 50, or by making nozzle50 adjustable.

Nozzle '50 may be made adjustable by providing in FIG. 5 cutoff plate'52 mounted by screws 53' in elongated parallel slots in the wall ofduct 48 to serve as an adjustable flow control gate means with its flowcontrolling edge 52a intercepting the flow through gas dis charge nozzle50. Pivoting plate 52 permits increasing or decreasing the quantity ofgas flowing through either end of nozzle 50 so as to obtain uniformquantity of gas flow over element width W. However, since edge 52a actslike a sharp edged orifice to laterally disperse stream 42, after itemerges from nozzle 50, to strike the radiating faces of burners 32 toprovide disadvantages mentioned in more detail hereinafter, it ispreferable to have nozzle 50 discharge a closely held together jet-likestream 42 as a thin layer of gas traveling over face F1 by originallydesigning nozzle 50 to provide this condition. Suitable gas turningvanes, baffles and tubular extension of nozzle '50 into nozzle duct 48are desirable to prevent this lateral dispersion.

It is desirable to have gas stream 42 directed toward surface F1 toincrease the scrubbing action and heat transfer action. This may be doneby so directing nozzle 50 or by adding gas stream deflector 54 mountedon gas over and along surface F1 but also toward and against surface F1,as seen by the arrows in FIG. 4, to serve with nozzle 50 as a gasdischarge directing means. Directing gas stream 42 toward and causing itto impinge against surface F1 has the advantage of increasing thescrubbing and heat transfer action when stream 42 strikes surface F1 aglancing blow and of protecting it against adversely affecting the flamegenerated infra-red radiation from flame-type infra-red burners 32.Water vapor in a boundary layer on surface F1 will also interfere withthe transmission of infra-red rays thereto and removal of convectionheat therefrom so that striking surface F1 by stream 42 is desirable tobreak up this boundary layer.

If gas stream 42 strikes the radiating face of burners 32, it appears toadversely affect the flame generated infraradiation from this flame-typeinfra-red burner 32 by either adversely affecting the flame or "byexcessively cooling the outer infra-red radiating surface on plate 7 inthe aforementioned Schwank patent. The flame may be adversely affectedby being blown out, sucked off the outer radiating surface of radiatingplate 7 in the Schwank patent by the Venturi effect under BernoullisTheorem, reduced in size, or at least adversely affected to reducesubstantially infra-red radiation output from the radiating platesurface by preventing proper flame combustion.

Although the gas flow characteristics of nozzle 50' will depend upon thegeometry of shapes, sizes and relative spacings of the components indrying apparatus 16 and of fabric element 12, it has been found in theinstallation in the aforegoing Table I that about 1500 cubic feet perminute of air at a discharge velocity of about 2000- feet per minute isthe maximum without adversely disturbing the flame generated infra-redradiation if screen 64 is not used, which screen will be described inmore detail hereinafter.

The gas moving means also includes gas exhaust opening 56 having atleast (and preferably much greater) flow cross sectional area than theflow cross sectional area of gas discharge nozzle 50 and being similarlyoriented with respect to surface F1 of element 12 but located on thedownstream side of gas stream 42 from heating zone 40 and dischargenozzle '50. Preferably, the mouth of exhaust opening 56 is larger indimension 50W than discharge nozzle 50 since gas stream 42 to beexhausted has swelled in volume since it has picked up heat and moistureso that a larger volume has to be exhaiusted through gas exhaust opening56 by exhaust fan 60 through duct 58 (having duct surfaces 58a andsuitable turning vanes 58b) and outlet duct 62 to the outside of dryingtower 14. Duct 62 is shown schematically in FIG. 1 as two verticaloutlet ducts for simplicity of illustration instead of the single outletduct 62 in FIGS. 2 and 3. Air grills 580, one in each duct '58, may beadjustably opened to adjust the draw in its associated opening 56 bycontrolling the admission of makeup air.

The efliciency of heat transfer and moisture vaporization and the highquality of fabric element 12 produced are readily apparent byconsidering the temperature of the air being exhausted in exhaustopening 56 and the temperature of fabric element 12 at the top end ofheating zone 40 in this typical apparatus 16 in tier T2 and bank B1. Inthe aforegoing Table I, the temperatures of fabric element 12 and of theexhausting air are without screen 64 (mentioned hereafter) respectively200 F. and 186 F. and with screen 64 respectively 160-180 F. and 164 F.Hence, there has been a good heat transfer and scrubbing action betweenair stream 42 and fabric element 12 and most of the infra-red energysupplied has gone into vaporizing water since neither the discharged gasnor fabric element are above the boiling point of water. Since element12 picks up very little more heat as it travels upwardly in tower 14 inFIG. 1, the temperature of element 12 can still be maintained at aboutonly 180-200 F. (from Table I) at the top of apparatus 16 in tier T8, if

so desired. Also, the fabric temperature of -200 F. is well below themaximum temperature before the aforementioned fibers are damaged byheat. For example, excessive heat when element 12, if made of certaintypes of nylon, still contains substantial amounts of water, might causechemical degradation at temperatures as low as 250 F. so element 12would not be damaged by drying apparatus 16 but might be damaged by the600 F. fabric temperature mentioned in the aforementioned Kersker US.Pat. No. 3,250,641 not using a high velocity gas stream.

If gas stream 42 is moving at too high of a velocity or if too large ofa quantity of gas is flowing in stream 42, the infra-red radiation fromflame-type burner 32 will be adversely affected, as aforedescribed.Reducing and eliminating this adverse effect has been found by insertionof a fine mesh gas deflecting screen 64, preferably mounted in frame 66secured by mounting brackets 93 and 94 in FIG. 6 directly to dischargenozzle duct 48 and exhaust opening duct 58; mounted between infra-redheater panel 31 and fabric element 12 to be dried; extending generallyparallel to fabric surface F1 in heating zone 40; and extendinggenerally parallel to the direction of movement T of fabric element 12.Various mesh screen has been tried, including 8, 10 and 12 mesh screen.The mesh of the screen and wire thickness control the gas streamvelocity-the finer the screen the higher velocity gas stream useable butthe less infra-red transmitted. It is best to use just coarse enoughscreen to handle the gas velocity. Coarse mesh screen has been used tosupport the fine mesh screen against warping. Stainless steel, Nichrome,and regular steel wire screen have been tried. The problems occurringwere warping, oxidation and brittleness under heat. It has been foundmost satisfactory to use an 8 mesh 0.023 inch wire diameter) ordinaryhardware cloth screen of inexpensive cost and to replace the screen whenit has been adversely damaged. Broadly speaking, this screen 64 is aburner shielding means intercepting the infra-red rays from the emittingsurface of infra-red panel heating surface 31 to element surface F1 inheating zone 40 for preventing adversely affecting the flame generatedinfra-red radiation, such as by shielding the flame on infra-red heaters32 from blowout, by gas stream 42 while permitting infra-red rays fromheaters 32 or heating means 28 to strike surface F1 in heating zone 40for drying. Broadly speaking, any suitable baffle means might be used inplace of screen 64.

Gas stream 42 and screen 64 coact to provide numerous advantages.Velocity of stream 42 discharging from nozzle 50 may be as high as 5000feet per minute with a flow of 3000 cubic feet per minute, and 6000 feetper minute velocities have been used, without adversely affectinginfra-red radiation from burners 32 in aforegoing Table I. Also, aportion of the gas layer in gas stream 42 moves across the fabric sideof screen 64 while heaters 32 are emitting infra-red heat so as toreduce any infra-red elevated temperature of screen 64 so as to prolongits useful life, to minimize warping and oxidation thereof, and topermit use of the aforementioned inexpensive hardware cloth. The highervelocity gas stream 42 substantially increases the speed of uniformdrying while still maintaining a controlled temperature. The fabricquality produced is still better and is produced on smaller sizedequipment. Hence, a great superiority is obtained by using screen 42even though a substantial improvement, as mentioned heretofore, wasobtained by using gas stream 42 without screen 64. Gas stream 42,traveling between fabric element 12 and screen 64, at high velocityaccelerates the drying while screen 64 diverts this gas from the flamegenerated radiating surface on burners 32 to allow efficient burneroperation. The higher velocity gas removes water vapor more quickly togreatly increase the drying efficiency while still maintaining fabrictemperature more uniform across dimension W and at a lower temperature.

Also, this fast drying action makes possible production of cord fabricwithout a webbed condition, wherein the adhesive liquid forms a hardenedfilm across the open mesh of the fabric securing adjacent cordstogether.

The substantial increase in drying rate and substantial reduction indrying equipment size is shown since drying tower 14 in FIG. 1 and TableI will dry coated element 18 (made of a particular fabric and weave) tothe same state of satisfactory dryness while traveling in direction Tin:

(1) Three tier heights when using screen 64 and 5000 f.p.m. air velocitystream 42 at nozzle 50.

(2) Five tier heights when using 3000 f.p.m. air velocity stream 42 atnozzle 50 and using no screen 64.

(3) Eight tier heights when not using either air stream 42 or screen 64.

This means that adding air stream 42 gives about a 38% reduction inheight of tower 14 and adding screen 64 and faster air stream 42 givesabout a 63% reduction in height of tower 14.

PLURALITY OF DRYING APPARATUSES 16 IN FIG. 2

In any given tier of drying apparatuses 16 in drying tower 14 in FIG. 1,such as tier T2, the two horizontally aligned drying apparatuses 16straddling opposite faces F1 and P2 of fabric element 12 have certaincommon structures, modes of operation and advantages as they coacttogether, as mentioned in more detail in the following paragraphsdescribing the stopping of element 12 and infra-red shutdown action,reflector side plates 90, gas flow ducts 92, elimination of back-upreflector to fabric element 12, and simultaneous drying and aeration ofboth sides of fabric element 12, etc.

When the driving action of drive rolls 22, 23 and 24 in FIG. 1 onelement 12 is shut down so as to stop the relative movement of element12, it is important in each of the sixteen drying apparatuses 16 intower 14 to immediately shut down infra-red radiation from heating means28 in all apparatuses 16 and to continue the flow of gas stream 42undiminished, by continued energization of the gas moving means, so asto relatively move gas stream 42 with respect to and over surfaces F1and P2 of element 12 in all heating zones so as to prevent residual heatfrom heating means 28 from raising the temperature of and damagingelement 12. This action will be described herein for only one or twodrying apparatus 16 since the sixteen in tower 14 are simultaneouslycontrolled in the same manner. Here, inlet fan 44 and exhaust fan 60 inFIGS. 2 and 3 operate continuously so as to run when fabric element 12is stopped as well as when it is being driven in the direction T duringfabric processing and drying. In fact, it is preferred to increase thegas quantity flowing in stream 42 during this infra-red shutdown becausefabric element 12 is not moving and cannot escape from heating zone 40,and infra-red heating means 28 has a great deal of residual heatradiating onto element 12. Also, increased gas flow now does notadversely affect radiation from gas infra-red burners 32 since they arenow shut down. Also, it is desirable either to cover the radiating faceof each panel 31 or to retract each panel away from fabric element 12and screen 64. The mechanism to be described hereafter provides thisaction for both drying apparatuses 16 in tier T2 in FIG. 1 (both inbanks B1 and B2), and is shown in more detail in FIGS. 2 and 7. In FIG.7, rotation actuated switch 68 (having its switch contact open duringstopping of drive roll 23 and having its switch contact closed whenfabric element 12 is being driven in direction T by the drive rolls)opens its switch contact upon stopping of movement of fabric element 12in direction T in heating zone 40 so as to de-energize each solenoid gasvalve 35 controlling main burner gas line 37 to each panel 31 in tier T2in FIG. 2 and de-energizes solenoid operated four-way valve 72 bybreaking their energizing parallel circuits between power lines L1 andL2. Deenergizing solenoid operated 4-way valves 72 connects air pressureline 73 to one end of double acting burner panel retracting cylinder 74and to one end of double acting gas flow damper cylinder 76 and connectsits exhaust port 72a to the other ends of these cylinders. This actionextends the length of cylinder 74 so that its upwardly moving piston rodin FIG. 2 swings arm 78 clockwise on pivot 79 so that bell cranks 80 onparallel pivot shafts 79, connected by link 82 will cause bell cranks 80to swing clockwise in FIG. 2 to retract panels 31 away from element 12from their solid line to their dot dash line positions since theopposite ends of links 82 and 84 and the distal end of arm 78 have pivotconnections. The upper end of each panel 31 is supported by at least onepair of trolley rollers 86 travelling in opposite channels of I-beam 87forming one of the upper structural members 14a in each apparatus 16 indrying tower 14. This action also causes double acting gas flow dampercylinders 76 to move quadrant-type damper 88 in FIG. 2 from a partiallyopen position in gas nozzle duct 48 assumed while fabric element 12 isdriven in direction T by the drive rolls during normal drying to a fullyopen position during infra-red shutdown to increase the gas dischargerate from nozzle 50 to increase gas stream 42 for cooling both screen 64and surfaces F1 and F2 of element 12 to protect them against residualheat from straddling heating means 28. When element 12 begins to travelin direction T, switch 68 closes to reverse this action so as to opengas valve 35, to contract cylinder 72 to advance panels 31 back to theirsolid line positions, and to move damper 88 back to its partially openposition so that each apparatus 16 is now ready for drying again. Duringthis reverse action, four-way valve 72 moves to its opposite position toconnect air pressure line 73 and its exhaust port 72a respectively tosaid other and said one ends of said cylinders in the conventionalfour-way valve operating manner to reverse the action of cylinders 74and 76.

Each of the two panels 31 in any given tier, such as tier T2 in FIGS.1-3, has secured to each of its vertical side surfaces in FIGS. 6 and 8reflector plate 90, four in number for each tier, adapted to telescopetogether over each edge of fabric element 12 in straddling relation shipwhen the burner panels are in their solid line positions in FIG. 2, asshown in FIG. 8. Then, these four reflector plates 90 form two generallyparallel reflector means extending along direction T of relativemovement of element 12 and straddling the opposite edges of element 12for heating these edges in heating zones 40 more uniformly by infra-redradiation by reflecting the infrared radiation back onto these edges ofthe fabric, since these edges would not otherwise get sufficientradiation since they are close to the edge of panels 31. Hence, thesereflector plates assure uniformity of infra-red radiation over fullwidth W of fabric 12 by capturing the infra-red radiation that wouldotherwise escape laterally through the gap between panels 31.

Flow ducts or flow channels 92 are formed, one duct on each side offabric element 12, for conveying the gas in each gas stream 42 as an aircurtain from its discharge nozzle 50 to its exhaust opening 56. Each gasflow duct 92 extends along the length of element 12, has element 12surface F1 and F2 as one wall thereof, and is mounted to receive gasstream 42 from discharge nozzle 50 for keeping gas stream 42 flowingover and close to this element surface and for discharging the gasstream 42 into discharge opening 56 for exhausting from drying tower 14.

Each vertically extending flow channel or duct 92 for gas stream 42 isformed by surface face F1 or P2 of element 12, reflector plates 90 andthe element 12 side face of screen 64 with these two ducts 92 each beingrectangular in cross section, generally parallel, and straddling elementsurfaces F1 and F2. Although each screen 64 may be secured to itsassociated burner panel 31, each screen 64 is preferably secured in FIG.6 at its upper and lower ends respecitvely by mounting brackets 93 and94 (one at each corner) to ducts 58 and 48 so that screens 64 will befixed against lateral movement relative to gas discharge nozzles 50 andelement surfaces F1 and F2 in heating zone 40, and therefore will notmove with panels 31 as they are retracted to the dot dash line positionsin FIGS. 2 and 6 during infra-red shutdown. Hence, there is constantgeometry between screens 64 and element 12 for controlling the thicknessof gas streams 42 straddling element 12, which geometry will not changeeven though-panels 31 are movable between these solid and dot' dash linepositions. Movement of reflector plates 90 with retractable burnerpanels 31 between the solid and dot dash line positions in FIGS. 2 and 6does not matter because they will return to their telescopedrelationship to form the sides of flow ducts 92 each time burner panels31 are moved to their advanced and solid line position in FIG. 2.

Each duct 92 plays an important part during travel of its stream 42 fromdischarge nozzle 50 to exhaust vent 56. Duct 92 guides, holds laterallycompact and prevents lateral dispersion stream 42 to maintain the flowaction of stream 42 in direction T along element 12 and toward exhaustvent 56 while keeping stream in close contact with element face F1 orF2.

Although two ducts 92 and four reflector plates 90 have now beendescribed for two apparatuses 16 in FIGS. 2, 3 and 8 for convenience, itshould be apparent that a single duct 92 straddled by only two reflectorplates 90 give the same advantages for a single apparatus 16. There areother advantages in having two drying apparatuses 16 facing each otherat each tier, such as tier T2 in FIG. 1, with one apparatus 16 in eachbank B1 and B2. Then, these two heating apparatuses 16 are mounted withtheir two heating zones 40 having sandwiched therebetween the generallycoinciding opposite faces F1 and P2 of element 12 so that each dries oneof the opposite generally coinciding parallel faces of element 12. Thisstructural arrangement and coaction has a higher drying heat;simultaneously dries both sides of fabric element 12; more rapidly driesfabric element 12; and requires no reflector behind element 12, such aswould be necessary if only one drying apparatus were used. Suchreflector frequently has a short useful wear life since it getstarnished and tends to melt under the hot infra-red radiation heat.

The eight drying apparatuses 16 in bank B1 in FIG. 1 in tires T1-T8arranged in series along direction T of travel of element 12 havecertain advantages. Each of these apparatuses 16 has its own gasdischarge nozzle 50 and gas exhaust opening 56 for generally uniformlyprocessing width W of element 12 in series arranged heating zones 40 aselement 12 moves upwardly in FIG. 1 past these eight series arrangeddrying apparatuses 16 in bank B1. Each of these eight drying apparatuseshas its own vertically traveling gas stream 42 formed from relativelyfresh, dry, cool air at ambient conditions sucked in from outside dryingtower 14 for its discharge nozzle 50 and has water molecule saturated,or at least heavily laden, air (substantially raised in temperature)exhausted through exhaust opening 56 and outlet duct 62 at the top ofdrying tower 14 so as to not interfere with the flow of fresh, dry airinto tower 14 for discharge nozzles 50. Having eight separate gasstreams 42 is a substantial advantage over having a single gas stream 42passing from the bottom to the top of drying tower 14. This single gasstream would (after it traveled more than one tier in height) be tooheavily laden with water molecules to provide an effective scrubbingaction, be too heated up to provide an eflective temperature control bycooling element 12, be too heavily concentrated with water molecules soas to prevent effective infra-red transmission from heaters 32 toelement 12, have lost its upward velocity so it would no longer scruboff the water molecules or remove the convection heat, not 'be able tobe kept confined to surface F1 or P2 of fabric element 12 because itwould lose its upward velocity, and not be able to be confined to acompact stream but would spread laterally and thus be totaHy useless.The advantage of dividing a single gas stream into eight separate seriesarranged gas streams 42 becomes more apparent when one realizes that thefree vertical travel of each gas stream 42 at each tier in FIG. 1 isabout eight feet vertically in the typical installation in Table I whilea single stream would have to travel about feet traveling the verticalheights of drying tower 14. Also, it is possible by using the sixteenseparate drying apparatus 16 in drying tower 14, arranged inhorizontally opposed pairs and in eight series arranged pairs,separately to control the infra-red heating action and flow of gasstream 42 in each component apparatus 16 to match the existing anddesired conditions of temperature and moisture removal from element 12as it is progressively dried as it moves vertically through drying tower14. This would not be possible if a single gas stream were used for thewhole height of tower 14. Also, it has been found during operation ofdrying tower 14 that the temperature of element 12 and the temperatureof the discharged air at the top of each tier T1-T8 can be controlled tobe approximately the same even though element 12 moves upwardly in tower14 and becomes progressively drier.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive with the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by U.S. Letters Patent is:

1. An apparatus for drying yarn or fabric fibers in a continuous lengthelement, comprising:

a heater with a flame for generating infra-red radiation,

disposed in a heating zone;

means for moving the continuous element past the heater; means formoving a stream of gas adjacent the heater in parallel and contactingrelation with the continuous element;

means separate from the heater and interposed between the heater andelement during normal operation of the heater to dry the fibers, forshielding the flame of the heater against the gas stream withoutdisrupting the infra-red radiation against the element.

2. The apparatus as set forth in claim 1, wherein the flame shieldingmeans includes a wire screen.

3. The apparatus as set forth in claim 2, which includes means forholding the wire screen in parallel relation to the moving element toform an air passageway for the gas stream.

4. The apparatus as set forth in claim 3, wherein the screen size isbetween 8-12 mesh.

5. An apparatus, as set forth in claim 1, with generally parallelreflector means extending along the direction of relative movement andstraddling the edges of said element for heating the edges of saidelement in said heating zone more uniformly by the infra-red radiationand for providing a flow channel for said gas layer in said heating zonestraddled on opposite sides by said element and by said shielding means.

6. A combination, comprising two of the apparatuses, as set forth inclaim 5, mounted with heating zones having sandwiched therebetweengenerally coinciding opposite element faces so that each dries one ofthe opposite generally coinciding faces of the element with said gasflow channels being generally parallel and straddling said element.

7. A combination, as set forth in claim 6, with each of said apparatusesincluding said burner shielding means being a screen extending generallyparallel to the direction of element relative movement, extendinggenerally parallel to the associated face of said element in saidheating zone, and being fixed against lateral movement relative to saidlast mentioned face in said heating zone,

said gas moving means having a portion of its gas layer moving acrosssaid screen during energization of said heating means for reducing anyinfra-red elevated temperature of said screen, and

heating cutoff means for moving said infra-red heating means relative tosaid screen and element during infra-red heating shutdown and stoppingof relative movement of said element with the relative positions of saidscreen, element in said heating zone, and gas discharge means beingmaintained,

said gas moving means being energized for relatively moving the gaslayer with respect to said last mentioned face of said element in saidheating zone during infra-red shutdown of said heating means andshutdown of said drive means for preventing residual heat from saidheating means from damaging said screen and said element not nowrelatively moving.

References Cited UNITED STATES PATENTS 3,406,954 10/1968 Fannon 2633JOHN J. CAMBY, Primary Examiner U.S. c1. X.R.

' g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3 5 ,375 Dated 7 7 Inventor) D. C. Sanders, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

instead of 209 180 gm 2 L iii- LLB mom mm mm I. W, m. Attesfin OfficerDominion at Patents

